On 9/10/20 11:08 am, Stephen John Smoogen wrote:
On Thu, 8 Oct 2020 at 17:50, Nicolas Kovacs <info@xxxxxxxxxxxxx> wrote:
Hi,
This is probably a bit OT, but here goes.
I've been running our local school's mail server since 2013, with mail
addresses for school staff and some teachers. The server is running CentOS
7
with Postfix and Dovecot, and it's a nice no-bullshit configuration with
SPF,
DKIM and DMARC.
The school sends quite a lot of email out to parents, and sometimes, mail
gets
rejected:
--8<--------------------------------------------------------
<xxxxxxxx@xxxxxxxxx>: host smtp-in.orange.fr[193.252.22.65] said: 550
5.2.0
Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
command)
<yyyyyyyy@xxxxxxxxxx>: host smtp-in.orange.fr[193.252.22.65] said: 550
5.2.0
Mail rejete. Mail rejected. ofr_506 [506] (in reply to end of DATA
command)
--8<--------------------------------------------------------
This happens randomly with the usual suspects among crappy mail providers
like
Orange, Hotmail/Live, Yahoo and the rest.
So wanadoo and orange seem to send a ofr_506 because the scanned mail was
found to be SPAM. This is independent of DKIM, SPF, DMARC but from them
scanning the email in the DATA and saying nope. Usually that is because too
many people complained about a set of email and the weight of email with
that content is getting blocked. I don't know if the school moving to
another provider will fix that as this isn't because of the IP it was sent
from (they block before the DATA is sent in that case). [My guess is that
someone wants to move to something else and is using this as the Casus
Belli to do so. ]
I don't really have a suggestion or solution to either problem..
If this reject is due to their spam filtering process, it is actually
the email author's problem - how they make up their sentences, key words
etc. and thus the problem will travel with them, to whatever email
provider they choose.
Suggest they get educated in how to write an appropriate email that
doesn't raise alarms, or they could use mailchimp (e.g. only) for their
large group emails.
Just a final thought - are the email address headers containing multiple
email addresses? this too can trigger blocking by some providers.
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